London taxi drivers use their smartphones as they stand alongside their parked cabs on The Mall, leading away from Buckingham Palace, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday,...More

London taxi drivers use their smartphones as they stand alongside their parked cabs...London taxi drivers use their smartphones as they stand alongside their parked cabs on The Mall, leading away from Buckingham Palace, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

A black London taxi cab passes a poster protesting against the Hailo smartphone app...A black London taxi cab passes a poster protesting against the Hailo smartphone app outside Waterloo train station, ahead of a protest against Uber Technologies Inc.'s car sharing service, in London, U.K., on Wednesday, June 11, 2014. More than 30,000 taxi and limo drivers from London to Milan plan to cause traffic snarls in tourist centers and shopping districts, in protest against the unregulation of Uber's car-sharing service. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

A London taxi driver places an identification board reading ' Totally Failing London' on the driver's window of his cab during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014....More

A London taxi driver places an identification board reading ' Totally Failing...A London taxi driver places an identification board reading ' Totally Failing London' on the driver's window of his cab during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

Rows of London taxi cabs stand parked outside Big Ben, right, and Portcullis House,...Rows of London taxi cabs stand parked outside Big Ben, right, and Portcullis House, center, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

British police officers stand alongside a black London taxi cab parked on Whitehall, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid...More

British police officers stand alongside a black London taxi cab parked on...British police officers stand alongside a black London taxi cab parked on Whitehall, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

British police officers are seen reflected in the window of a London taxi cab during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and...More

British police officers are seen reflected in the window of a London taxi cab...British police officers are seen reflected in the window of a London taxi cab during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

A demonstrator holds a placard as he stands between lines of London taxi cabs parked on Whitehall, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in...More

A demonstrator holds a placard as he stands between lines of London taxi cabs...A demonstrator holds a placard as he stands between lines of London taxi cabs parked on Whitehall, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

A London taxi driver leans against the diver's door of his cab as he reads 'The Badge' newspaper, whilst parked along The Mall, leading away from Buckingham Palace during a protest against Uber Technologies Inc.'s car sharing service...More

A London taxi driver leans against the diver's door of his cab as he reads 'The...A London taxi driver leans against the diver's door of his cab as he reads 'The Badge' newspaper, whilst parked along The Mall, leading away from Buckingham Palace during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

Tape covers a Hailo logo on the hood of a yellow London taxi cab parked on Trafalgar Square, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts...More

Tape covers a Hailo logo on the hood of a yellow London taxi cab parked on...Tape covers a Hailo logo on the hood of a yellow London taxi cab parked on Trafalgar Square, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore

Pedestrians walk past rows of London taxi cabs parked outside Big Ben and the...Pedestrians walk past rows of London taxi cabs parked outside Big Ben and the Houses of Parliament, during a protest against Uber Technologies Inc.'s car sharing service in London, U.K., on Wednesday, June 11, 2014. Traffic snarled in parts of Madrid and Paris today, with a total of more than 30,000 taxi and limo drivers from London to Berlin blocking tourist centers and shopping districts. Photographer: Simon Dawson/Bloomberg via Getty ImagesLessMore